It is previously known to provide ducts within a truck hood to deliver air from the vehicle exterior to the engine. U.S. Pat. No. 3,232,368 to Sullivan teaches a molded fiberglass hood having a rear reinforcement beam bonded to the skin which defines a duct opening through the skin at the rear portion of the hood sides. Within the engine compartment, the duct interfaces with the engine air cleaner to draw induction air into the engine.
Although there are commercial vehicles which utilize a hood ducting system similar to that of Sullivan, the external air inlets are typically located on the top or sides of the hood adjacent the rear portion thereof, to achieve the shortest passage and, accordingly, the minimum air restriction at the engine. However, these short passages also result in road splash, water, dirt, and other contaminants to be drawn into the hood ducts to be dealt with by the engine air cleaner.
The problem of contaminant materials has been addressed by providing a baffle structure into the air duct. However, providing a baffle structure into the air duct reduced the air flow in the duct, causing an increase in the pressure drop in the duct. In turn, the increase in pressure drop increases the amount of work the engine performs to obtain air for combustion.